Practical amphibious vehicles generally have their engines mounted either centrally or in the rear of the vehicle so as to ensure a ‘nose up’ attitude when under way in marine mode. One such example of this conformation is as shown and described in Japan se Patent Publication No 63-093607 (Mazda Motor Corp). This Mazda proposal is for an amphibious vehicle having a transverse rear mounted engine arranged to drive selectively rear road wheels and/or, through an axial transmission, a marine propulsion unit in this case a pump jet. More particularly the engine is mounted at least partly above the rear road wheel driving axles. The pump jet is driven by a shaft from a gearbox called a “transfer device”. The transfer device is so designed to power front road wheels or the pump jet as required and is itself driven from the engine via a ring gear on a differential. The transfer device is mounted ahead of the engine. The result of this Mazda conformation is that it is necessary to mount the engine above the pump jet driveshaft. This shaft is in turn central to the marine pump jet, which must be mounted to provide adequate ground clearance at the tail of the vehicle to give an adequate ramp angle when the vehicle is in road mode. Consequently the centre of gravity of the vehicle is higher than it would be for an equivalent purely marine craft. Again because it is not possible to ballast an amphibious vehicle any increase in the height of the centre of gravity relative to the centre of buoyancy is significant when considering roll in marine mode for a vehicle with a low freeboard.
It is therefore an object of the present invention to reduce the height of the centre of gravity relative to the centre of buoyancy so as to increase the stability of the amphibious vehicle commensurate with adequate ground clearance.